docs: def thumbnail(self, value):
          """
          gets/sets the thumbnail
          Enter the pathname to the thumbnail image to be used for the item.
          The recommended image size is 200 pixels wide by 133 pixels high.
          Acceptable image formats are PNG, GIF, and JPEG. The maximum file
          size for an image is 1 MB. This is not a reference to the file but
          the file itself, which will be stored on the sharing servers.
          """
          if os.path.isfile(value) and \
             self._thumbnail != value:
              self._thumbnail = value
          elif value is None:
              self._thumbnail = None